Standpipes are traditionally installed in cellars, basements, or other low points in buildings to prevent water backup in sewer drains incident to heavy rain, thawing, or run off. An upright pipe is extended upwardly from a sewer pipe or a region in the subsurface generally as high as two to three feet above the floor surface. A coupling member is embedded in the floor and receives the standpipe threadably, or in any other suitable manner.
Two problems are most prevalent in the prior art standpipe construction. First, leaks often develop around the base of the standpipe which causes flooding in the surrounding area. Second, when the standpipe is too tall, the subsurface pressure may rupture the floor before pressure relief is afforded at the top of the standpipe.
U.S. Pat. No. 2,891,575, issued to A. Moeller, addresses the leakage problem. In Moeller, a stopper portion, consisting of a compressible resilient body, is inserted into a recessed sewer drain bowl. The body is compressed by means of an elongated adjusting rod, which extends up the length of the standpipe, until the expanded body makes leakproof engagement with the drain bowl. The only pressure relief afforded is by the air escape openings adjacent the top of the standpipe.
An alternate standpipe construction is shown in U.S. Pat. No. 2,478,976, issued to C. Modlin. Modlin discloses a series of axially aligned telescoping standpipe segments. Under normal conditions, the standpipe does not protrude above the floor level. The sections are extended progressively in response to an increasing subsurface pressure. With the standpipe fully extended, a stopper is buoyed against the top wall to seal the openings. The unbuoyed stopper permits drainage for surface water when the standpipe is retracted.
The present invention is directed to overcoming the aforementioned problems.